The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Known portable power tools typically have an electric motor received within a tool housing. One common type of electric motor used in power tools has a rotor, a stator, and brushes. The rotor includes a rotor shaft, laminations mounted on the rotor shaft, armature windings wound in slots in the lamination stack, and a commutator mounted on the rotor shaft and electrically connected to the armature windings. Coils are wound into the lamination slots. End insulators are sometimes used at the ends of the lamination stack. Some end insulators may be shaped to maximize the amount of coil wire wound into the lamination stack slots, as described in U.S. Patent Publication No. 2013/0313940, content of which is incorporated herein by reference in its entirety. The coils of the armature are typically covered via a coating of electrically insulating material.
The stator may have field windings wound in laminations, or may have permanent magnets. The brushes are mounted in brush housings, often known as brush boxes or brush holders, in sliding electrical contact with the commutator. Electric current is supplied from a power source through the brushes to the commutator, and from the commutator to the armature windings.
Generally, electric motors include a fan attached to the armature. The fan rotates along with the armature to cool the motor stator, armature, and commutator. The fan generally includes a plurality of fan blades that dispel air centrifugally, thus generating air flow through the stator, armature, and the commutator.
Some conventional fans are mounted onto the armature shaft. This arrangement, however, requires axial spacing on the shaft dedicated to the fan, which adds to the total length of the motor. Alternatively, the fan may be attached to the end of the armature. However, tolerances associated with the armature coil and the insulating coating are often too large, which would make it difficult for the fan to be assembled with precision. Also, attaching the fan to the insulating coating of the armature securely presents additional challenges, since it is not easy to bond powder coating and plastic material together. What is therefore needed is a motor in which the fan is mounted to the armature in a compact and easy to manufacture way.